img {
    display: block;
    width: 100%;
    height: 100%;
  }

  a,
  a:hover,
  a:active {
    text-decoration: none;
    color: black;
  }


  .banner {
    width: 600px;
    height: 400px;
    border: 5px solid #000;
    margin: 50px auto;

    position: relative;

    overflow: hidden;
  }

  .banner ul {
    width: 500%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
  }

  .banner ul::after {
    display: block;
    content: "";
    clear: both;
  }

  .banner ul li {
    float: left;
    width: 600px;
    height: 400px;
  }

  .banner ol {
    height: 50px;
    background: rgba(0, 0, 0, 0.5);
    position: absolute;
    bottom: 50px;
    left: 50%;
    transform: translateX(-50%);
    padding: 10px;
    border-radius: 10px;

    display: flex;
    justify-content: center;
    align-items: center;
  }

  .banner ol li {
    width: 30px;
    height: 30px;
    background: #fff;
    border-radius: 50%;
    margin: 0 10px;
    cursor: pointer;
  }

  .banner ol li.active {
    background: red;
  }

  .banner div {
    width: 100%;
    height: 50px;
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);

    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .banner div a {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 50px;
    height: 50px;
    font-size: 40px;
    color: orange;
  }